Scanning Hall probe microscope images of field penetration into niobium films

James, Sebastian S.; Field, Stuart B.; Seigel, J; Shtrikman, Hadas

doi:10.1016/s0921-4534(99)00721-2

Cited by 16 publications

(26 citation statements)

References 13 publications

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“…We show that when quenched disorder is included in the diffusion equation, the flux front roughens and is eventually pinned. Varying the parameters of the model (applied field, disorder, interaction strength), the fluctuations of the front display a crossover from flat to fractal that is consistent with experimental observations [5][6][7]. The value of the fractal dimension suggests that the strong disorder limit is described by percolation.…”

supporting

confidence: 79%

“…A different approach treats the problem at mesoscopic scale, describing the evolution of interacting coarse-grained units [14,15], supposed to represent the system at an intermediate scale. While these models give a faithful representation of several features of the problem, the connection with the underlying microscopic dynamics remains unexplored.In this Letter, we investigate the invasion of magnetic flux into a disordered superconductor, a problem that has recently been the object of intense experimental research [5][6][7]. We first analyze the problem by MD simulations, in analogy with Ref.…”

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confidence: 99%

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Flux Front Penetration in Disordered Superconductors

2001

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We investigate flux front penetration in a disordered type-II superconductor by molecular dynamics simulations of interacting vortices and find scaling laws for the front position and the density profile. The scaling can be understood by performing a coarse graining of the system and writing a disordered nonlinear diffusion equation. Integrating numerically the equation, we observe a crossover from flat to fractal front penetration as the system parameters are varied. The value of the fractal dimension indicates that the invasion process is described by gradient percolation.

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confidence: 79%

mentioning

confidence: 99%

Flux Front Penetration in Disordered Superconductors

2001

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“…While the Bean model provides a consistent picture of average magnetization properties, such as the hysteresis loop and thermal relaxation effects [30], it does not account for local fluctuations in time and space. It has been recently observed that flux line dynamics is intermittent, taking place in avalanches [31], and flux fronts are not smooth [32][33][34]. In particular, it has been shown that the flux front crosses over from flat to fractal as a function of material parameters and applied field [33].…”

Section: Gradient Driven Dynamics: Front Invasionmentioning

confidence: 99%

Deblocking of interacting particle assemblies: from pinning to jamming

Miguel¹,

Andrade²,

Zapperi³

2003

Braz. J. Phys.

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A wide variety of interacting particle assemblies driven by an external force are characterized by a transition between a blocked and a moving phase. The origin of this deblocking transition can be traced back to the presence of either external quenched disorder, or of internal constraints. The first case belongs to the realm of the depinning transition, which, for example, is relevant for flux-lines in type II superconductors and other elastic systems moving in a random medium. The second case is usually included within the so-called jamming scenario observed, for instance, in many glassy materials as well as in plastically deforming crystals. Here we review some aspects of the rich phenomenology observed in interacting particle models. In particular, we discuss front depinning, observed when particles are injected inside a random medium from the boundary, elastic and plastic depinning in particle assemblies driven by external forces, and the rheology of systems close to the jamming transition. We emphasize similarities and differences in these phenomena.

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“…Indeed, recent experiments showed that these fluctuations are not only common, but also large, spanning several length scales: the flux line dynamics is intermittent, taking place in avalanches, 4 and flux fronts are fractal. [5][6][7] A widely used modeling strategy to describe the fluctuations in the magnetization process consists in molecular dynamics ͑MD͒ simulations of interacting vortices, pinned by quenched random impurities. [8][9][10][11] With this approach it has been possible to model flux profiles, 9 hysteresis, 9 avalanches, 10,11 and plastic flow.…”

Section: Introductionmentioning

confidence: 99%

Boundary effects on flux penetration in disordered superconductors

et al. 2002

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We investigate flux penetration in a disordered type-II superconductor by molecular dynamics simulations of interacting vortices. We focus on the effect of different boundary conditions on the scaling laws for flux front propagation. The numerical results can be interpreted using a coarse-grained description of the system in terms of a nonlinear diffusion equation. We propose a phenomenological equation for the front position that captures the essential behavior of the system and recovers the scaling exponents.

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Scanning Hall probe microscope images of field penetration into niobium films

Cited by 16 publications

References 13 publications

Flux Front Penetration in Disordered Superconductors

Flux Front Penetration in Disordered Superconductors

Deblocking of interacting particle assemblies: from pinning to jamming

Boundary effects on flux penetration in disordered superconductors

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